Oil pressure light?

[SeventhEclipse]

I was driving my car home from work today, and after about 20 miles my oil pressure light turned on. I looked at my oil pressure gauge and it was reading about 40 lbs, but I still pulled over to check the oil. So I started it back up and got about twenty more miles before it came back on!!!! So can anyone tell me at what oil pressure the the warning light is supposed to come on??? Or if this just sounds like a faulty sending unit???

 

[92AWDHX40]

I never knew of a number when it comes on i check my oil, do you have oil in the car, may be a simple sender broken or going bad..

 

[SeventhEclipse]

Yes I checked the oil, Its full. That's why I was wondering If there is a pressure it may have dropped to that caused the light to turn on.